1. Field of the Invention
This invention relates generally to electronic devices, and more particularly to heat sinks for providing thermal management of electronic devices, including semiconductor chips.
2. Description of the Related Art
Circuit boards, such as printed circuit boards, are used in a vast array of electronic devices. Examples of such devices are legion, and include devices as diverse as ultrasound machines and cellular telephone handsets. A typical conventional circuit board includes a substrate upon which several components are mounted. The components can include integrated circuits, and passive devices such as capacitors, resistors and inductors. In some applications, the circuit board itself or one or more components mounted thereon may dissipate sufficient amounts of heat so that thermal management may be necessary. This may be due to the potential for the undissipated heat to adversely affect the performance or damage components of the device and/or for the heat to cause the temperature of the device in question to climb above a comfortable level for user handling.
Many conventional circuit boards that require thermal management utilize a heat sink of one design or another. Conventional heat sinks are frequently fabricated from a thermally conducting metallic material, such as copper or aluminum. These types of heat sinks can affect the electronic performance of the component requiring thermal management or other components that may be affected by emissions from the heat sink itself. For example, the component requiring thermal management may receive spurious signals associated with the heat sink or have its own emissions, as in the case of a communications device, attenuated or otherwise degraded by the action of the heat sink. Similarly, the heat sink may create or change emissions that may effect the performance of other components on the circuit board.
A given conventional heat sink may be qualified for a particular application by making an assessment of the heat sink's electromagnetic compatibility (EMC). Typically, the EMC of a given heat sink and circuit board combination involves a determination of the level of emissions generated by the heat sink and an assessment of whether those emissions exceed a specification for the combination as well as a determination or a measurement of potential signal attenuation associated with the heat sink. In typical conventional heat sink designs, the EMC of the heat sink and circuit board combination is determined by the number and location of grounding points for the heat sink to the circuit board. Usually this involves grounding the heat sink at certain known ground pad locations on the circuit board. The selection of the grounding points for a given conventional heat sink is typically set in advance. In essence, once the conventional heat sink is fabricated, the location and number of grounding points will be set. If, thereafter, the combination of the heat sink and the circuit board in a given application fails to meet EMC, then there will be relatively few choices to try to change the grounding characteristics for that particular heat sink and circuit board combination.
The present invention is directed to overcoming or reducing the effects of one or more of the foregoing disadvantages.